A startling new study from Jonathan Bearak, a senior research scientist at the Guttmacher Institute and a Ph.D. at NYU, found that students who have casual sex in college are less likely to use condoms after their sophomore year.

The study, published in 2014 in the journal Social Forces, looked at 7,144 female and 3,131 male college students around the country. Bearak found that seniors are about two-and-a-half times more likely to have unprotected casual sex than freshmen are. The study also found that the most significant drop in condom use happens during sophomore year.

In addition, it seems that the students who are most likely to change their condom use are students from disadvantaged backgrounds. Bearak found that students from disadvantaged backgrounds are more likely to use condoms when they enter college than their more privileged peers. Then the number drops off. “It's ironic because students are actually learning bad behaviors, and they're learning it from the group of students who policymakers would generally say they want the least advantaged students to emulate,” Bearak told NPR.

Condoms/Paul Keller - flickr.com

Dr. Karen Rayne, a sex educator and speaker based in Austin, Texas, says that these findings are troubling. Declining condom use in any population will eventually lead to a greater sexually transmitted infection (STI) rate, Rayne said. “It may take a while to see the difference but after a while it’s going to be passed around very quickly,” Rayne said. However, Rayne explained that more research on this particular finding needs to be conducted.

This is among the first research comparing condom use among college students at different stages in their college career. However, a previous study published in the Journal of Public Health in 2010 found similarly low levels of condom use among college aged students: only 60% of the persons in the student sample had used condoms in the last 6 months, and less than one half definitely intended to use condoms in the next month. Bearak’s study puts us a step closer to figuring why the rate of condom usage is lower than recommended.

“College may not discourage condom use directly, but rather…[places] them in social situations that do not encourage condom use,” Bearak wrote in his study.

For more on the importance of sexual health, check out this piece on why you deserve more effective condoms.